git: kernel - Refactor the vmspace locking code and several use cases

From:

Matthew Dillon <dillon@xxxxxxxxxxxxxxxxxxxxxxx>

Date:

Thu, 1 Dec 2011 17:09:56 -0800 (PST)

commit a2ee730d0cec9395df7e733b2ca627cccbb0633a
Author: Matthew Dillon <dillon@apollo.backplane.com>
Date: Thu Dec 1 16:54:19 2011 -0800
kernel - Refactor the vmspace locking code and several use cases
* Reorder the vnode ref/rele sequence in the exec path so p_textvp is
left in a more valid state while being initialized.
* Removing the vm_exitingcnt test in exec_new_vmspace(). Release
various resources unconditionally on the last exiting thread regardless
of the state of exitingcnt. This just moves some of the resource
releases out of the wait*() system call path and back into the exit*()
path.
* Implement a hold/drop mechanic for vmspaces and use them in procfs_rwmem(),
vmspace_anonymous_count(), and vmspace_swap_count(), and various other
places.
This does a better job protecting the vmspace from deletion while various
unrelated third parties might be trying to access it.
* Implement vmspace_free() for other code to call instead of them trying
to call sysref_put() directly. Interlock with a vmspace_hold() so
final termination processing always keys off the vm_holdcount.
* Implement vm_object_allocate_hold() and use it in a few places in order
to allow OBJT_SWAP objects to be allocated atomically, so other third
parties (like the swapcache cleaning code) can't wiggle their way in
and access a partially initialized object.
* Reorder the vmspace_terminate() code and introduce some flags to ensure
that resources are terminated at the proper time and in the proper order.
Summary of changes:
sys/kern/imgact_resident.c | 2 +-
sys/kern/kern_exec.c | 19 ++---
sys/vfs/procfs/procfs_mem.c | 2 +
sys/vm/device_pager.c | 5 +-
sys/vm/swap_pager.c | 5 +-
sys/vm/vm_extern.h | 4 +
sys/vm/vm_glue.c | 2 +-
sys/vm/vm_map.c | 176 ++++++++++++++++++++++++++++---------------
sys/vm/vm_map.h | 8 ++-
sys/vm/vm_object.c | 21 +++++-
sys/vm/vm_object.h | 1 +
sys/vm/vm_vmspace.c | 6 +-
sys/vm/vm_zone.c | 1 +
13 files changed, 170 insertions(+), 82 deletions(-)
http://gitweb.dragonflybsd.org/dragonfly.git/commitdiff/a2ee730d0cec9395df7e733b2ca627cccbb0633a
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